Security readout for executives and security teams
Plain-English summary
This is a remote code execution issue in Microsoft Exchange Server. A successful attacker could gain full confidentiality, integrity, and availability impact, but the CVSS vector indicates high privileges are required. Because CISA lists it in KEV, treat it as known exploited and prioritize remediation of affected Exchange servers.
Executive priority
High priority. Exchange is business-critical infrastructure, and KEV status means exploitation has been observed. The privilege requirement lowers some likelihood, but successful exploitation has severe impact. Remediation should be handled as an urgent server maintenance and risk-closure item.
Technical view
CVE-2021-31196 affects specified Microsoft Exchange Server 2013, 2016, and 2019 cumulative updates. CVSS 3.1 is 7.2 with network access, low complexity, high privileges required, no user interaction, unchanged scope, and high CIA impact. The bundle does not identify a CWE or vulnerable component.
Likely exposure
Organizations running Exchange Server 2013 CU23, Exchange Server 2016 CU20 or CU21, or Exchange Server 2019 CU9 or CU10 are the stated exposure set. Internet-facing Exchange servers and systems administered by many privileged users deserve first review.
Exploitation context
CISA KEV inclusion supports active exploitation. The source bundle does not provide exploit mechanics, public exploit availability, or observed campaign details. The CVSS vector indicates exploitation requires high privileges, so this is not described as unauthenticated remote compromise.
Researcher notes
Evidence is limited to the CVE description, affected CUs, CVSS vector, Microsoft advisory reference, and CISA KEV status. Do not infer unauthenticated exploitation or affected components from this bundle. Validate by product version, CU, and applied Microsoft update state.
Mitigation direction
- Apply Microsoft’s official guidance for the affected Exchange cumulative update.
- Prioritize remediation on internet-facing and high-business-impact Exchange servers.
- Retire or upgrade affected cumulative updates that cannot receive the official fix.
- Track closure against CISA KEV-driven remediation expectations.
Validation and detection
- Inventory Exchange Server versions and cumulative update levels.
- Identify Exchange 2013 CU23, 2016 CU20/CU21, and 2019 CU9/CU10 systems.
- Confirm installed security-update state against Microsoft’s CVE advisory.
- Check vulnerability management records for CVE-2021-31196 remediation status.
- Document any remaining affected servers and compensating controls.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
Execution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-31196 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.2 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C1.25.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.2HighVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31196CVE reference · x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31196CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.